1. Field of the Invention
This invention relates to a process for forming an image and to an image recording material. More specifically, it relates to a process for forming an image using a metal layer and an inorganic material layer which are superimposed, and to an image recording material for use in such a process.
2. Description of the Prior Art
It is already known from the disclosures of U.S. Pat. No. 3,637,377 - 381 that when a certain metal and an inorganic compound are superimposed by, for example, vacuum evaporation, and then subjected to electromagnetic radiation, the irradiated part of the metal layer diffuses into the inorganic compound layer, and the luster of that part of the metal layer disappears. This phenomenon is also called photodoping because the metal is doped utilizing light, and various methods for forming images utilizing this phenomenon have been proposed.
According to photodoping, positive-positive type images are always obtained since the exposed portion of the metal layer diffuses into the inorganic compound layer. It is impossible therefore to utilize photodoping when negative-positive type images are desired.
In the course of our investigations into the formation of images using heat, it was found surprisingly that when a metal layer and an inorganic compound layer are superimposed and after exposure, heated, the metal layer at the unexposed areas diffuses into the inorganic compound layer and the luster of these portions disappears (this phenomenon will be referred to hereinafter as "thermal doping").
It is therefore an object of this invention to provide a process for forming negative-positive type images.
Another object of this invention is to provide an image forming material capable of furnishing negative-positive type images.